General Comments on Tolerancing Limits
This represents a general list of soft limits and is intended for reference only.
Reducing tolerance range increases costs.
Robust sensitivity analyses will help yield the most cost-effective tolerancing.
Tolerancing Limits for Cylinder Surfaces
|wdt_ID||Attribute||Cylinder Tolerancing Limit|
|1||Glass Quality (nd, vd)||Melt Rebalanced and Controlled|
|2||Length and width (mm)||+0, -0.020|
|3||Center Thickness (mm)³||± 0.020|
|4||Sag – Concave (mm)||± 0.020|
|6||Radius⁵||± 0.1% or 3 HeNe fringes⁶|
|7||Irregularity – Interferometry (HeNe fringes)⁷||0.1⁸|
|8||Irregularity – Profilometry (μm)||± 0.5|
|9||Plano Axis Wedge – ETD (mm)||0.005¹²|
|10||Cylinder Axis Decentration – TIR (mm)⁹||0.010¹⁰|
|11||Axial Twist Angle (arcminutes)||3|
|12||Bevels – Face Width @ 45° (mm)¹¹||0/0mm max|
|13||Scratch – Dig (MIL-PRF-13830B)¹²||10 – 5|
|14||Surface Roughness (Å RMS)¹³||5|
- This is for the most well behaved materials. More difficult materials (CaF2, Ohara S-FPL, etc.) will need larger tolerance ranges.
- Of full aperture (FA).
- In addition to irregularity.
- Whichever is correspondingly larger over the clear aperture.
- Typical metrology is Zygo MetroPro plots for interferometry.
- As geometry requirements move closer to a min or max shown the less likely this is possible.
- Optimax measures total indicated runout (TIR) as part is rotated. Actual decentration varies with focal length.
- This specification is extremely tight and expensive. For a more economical limit, please consider using 0.0100mm.
- Subject to measurement uncertainty.
- Crystals and reflective materials will receive 40W inspection.
- This represents lowest values obtained. Actual values for crystalline, especially polycrystalline materials, will be higher.